1. Field of the Invention
The present application relates generally to devices for delivering respiratory gas or gases in medical applications, and more particularly, to a new and improved respiratory face mask and breathing circuit assembly that is especially useful in administering gases, such as anesthesia inhalation agents, or oxygen, or air, or mixtures of same, for medical purposes, and as such represents an improvement over the similar device or devices disclosed in my prior applications.
2. Description of the Prior Art
In my prior applications, I fully disclose a disposable anesthesia face mask assembly having a flexible hollow inflatable sealing cushion extending along substantially the entire peripheral edge of the mask shell or body member to prevent anesthesia gas or the like delivered through the gas portal on the mask from escaping and adversely affecting the surgical environment. The unique face mask assembly disclosed in my prior applications represents a significant advance over the prior art because, inter alia, it is the only respiratory or anesthesia mask now known having a pneumatic sealing cushion that extends over and under the chin portion of the patient's face and surprisingly, as a result of this unique arrangement, requires only a relatively simple single headstrap or band for maintaining the mask in a stable position even during long duration surgical procedures. Hence, the mask and headstrap assembly of my prior applications are ideally suited for use during so-called “sedation” anesthesia procedures where the patient breathes on its own.
A well-known safe and effective sedation anesthetic in gas inhalation form is nitrous oxide (N2O). This compound, frequently called “laughing gas” or “happy gas,” has been used medically for many years usually as an analgesic or “light sedative” to ease pain associated with trauma, childbirth or heart attacks, for example, or as a carrier for more potent anesthesia gases (e.g. Desflurane, Sevoflurane). Indeed, nitrous oxide is so safe, easy to handle, and readily available relatively inexpensively, it has been used as an anesthetic in dentistry since the 1800s. When used by a dentist, nitrous oxide is typically administered through a demand-valve or continuous inhaler placed over the patient's nose so that the patient's mouth can be worked on while the patient continues to inhale the gas. A full face-mask therefore cannot be used in dentistry, and to avoid build-up of exhaled or waste nitrous oxide, which can pose an intoxicating and prolonged-exposure hazard to the clinic staff in the room where the procedure is being conducted, a continuous-flow-fresh-air ventilation system or nitrous-scavenging system must be used.
In “Case Series of Nurse-Administered Nitrous Oxide for Urinary Catheterization in Children,” Anesthesia & Analgesia 2007; 104:876-879, Judith L. Zier, M. D. et al, the authors reported the use of N2O to “sedate” children undergoing a painful procedure in a hospital setting. Administration of the nitrous was carried out using commercially available “dental” equipment to supply the N2O gas and to scavenge exhaled waste (through a nose mask). Thus, the authors reported that a “comfortable seal could be maintained . . . over the nose of the older child” (emphasis added). Nitrous oxide is only minimally metabolized in the human body. Accordingly, unless provision is made to collect or otherwise scavenge the breath of a patient exhaled through the mouth, build up of exhaled N2O waste gas in the hospital environment using such “dental equipment” cannot reasonably be avoided.
In order to overcome the foregoing disadvantages, the present application discloses a new and improved respiratory face mask and breathing circuit assembly adapted to be used with commercially available nitrous oxide gas handling equipment used in dentistry. When so employed, the disposable respiratory face mask and breathing circuit assembly of the present invention completely avoids contaminating the surrounding environment with built-up waste N20 gas thereby facilitating safe and effective combined use of such equipment for sedation purposes in a hospital or other clinical environment. An enclosed environment is not exposed to exhalation gas received from said disposable respiratory face mask because a novel breathing circuit is disposed in fluid communication between said disposable respiratory face mask, a gas delivery device, and a vacuum source.